Researchers Discover Mechanism Behind Sunburn

Sun exposure is a key factor in skin cancer, and the number of cases has doubled over the last few decades. Tourists sunbathe at Illetas beach on the Balearic island of Mallorca June 4, 2008.
Dani Cardona/ Reuters

Researchers have now found the mechanism of sunburn. The red, inflamed skin associated with sunburn is a result of ultraviolet (UV) damage to RNA found in skin cells.

According to researchers, the discovery could help find ways to treat various diseases associated with sunburns and even cancers.

"For example, diseases like psoriasis are treated by UV light, but a big side effect is that this treatment increases the risk of skin cancer. Our discovery suggests a way to get the beneficial effects of UV therapy without actually exposing our patients to the harmful UV light. Also, some people have excess sensitivity to UV light, patients with lupus, for example. We are exploring if we can help them by blocking the pathway we discovered," said Richard L. Gallo, MD, PhD, professor of medicine at UC San Diego School of Medicine and Veterans Affairs San Diego Healthcare System and lead author of the study.

Researchers worked on both human and mouse cells and found that the UVB radiation damages the non-coding micro-RNA in the cell. The miRNA is a special type of RNA inside the cell. The skin cells damaged by UV radiation release this altered mi-RNA. In time, the neighboring cells respond by starting the inflammation process to remove all damaged cells, which is the inflamed skin associated with sunburn.

Although this process happens so that the cells do not become cancerous, but more UV exposure increases the risk that these cells can become cancerous.

"The inflammatory response is important to start the process of healing after cell death. We also believe the inflammatory process may clean up cells with genetic damage before they can become cancer. Of course, this process is imperfect and with more UV exposure, there is more chance of cells becoming cancerous," said Gallo.

"Genetics is closely linked to the ability to defend against UV damage and develop skin cancers. We know in our mouse genetic models that specific genes will change how the mice get sunburn. Humans have similar genes, but it is not known if people have mutations in these genes that affect their sun response," said Gallo.